The present invention relates generally to amplifier redundancy systems, and more particularly, to a gain and phase balanced amplifier redundancy system suitable for use in satellite communications payloads.
A typical satellite communications payload includes an output section that may contain multiple amplifiers. These amplifiers are sometimes configured such that satellite communications signals, intended for a user on the ground, pass through more than one amplifier to generate a large amount of output power (more than is capable of being delivered by a single amplifier). This type of system is sometimes referred to as a matrix amplifier system.
For matrix amplifier systems, the phase and amplitude of the signals passing through each amplifier path are significant because these signals combine with a specific phase to achieve a power distribution among satellite antenna radiating elements, which is required to obtain a proper antenna pattern.
Redundancy ringsnetworks having redundancy switches are often included in such amplifier arrangements to prevent the failure of a single amplifier from degrading an entire payload performance.
Typically, redundancy switches are used to switch out the failed amplifier and switch in an additional redundant amplifier held in reserve. For example, if four amplifiers are normally required, five amplifiers may be placed in the payload (one redundant amplifier). This is called a five-for-four redundancy. Other systems might be used depending on the reliability of the amplifiers, for example, six-for-four redundancy, three-for-two, etc.
A typical amplifier redundancy system, such as the five-for-four system, includes a plurality of inputs and a plurality of amplifiers associated thereto. For example, a first signal at a first input is amplified by the first amplifier, a second input is amplified by a second amplifier, etc. Important to note is that the line length from the input to an output passing through one of the amplifiers may be different than the line length from an input to the output passing through an extra amplifier due to the physical size of the amplifier, difference in line length through the switch, etc.
The aforementioned difference in line length causes the phase of each signal paths to be different for both no failure and redundant cases. In current designs, particularly designs in which matrix amplifier systems are used to provide flexibility and power allocation to different antenna beams, the phase change causes some power to exit undesired matrix ports, changing the antenna pattern and degrading payload performance.
Alternate systems include redundant amplifiers placed centrally to reduce the number of switches that must be reconfigured to switch in the redundant amplifier. Usually, the input side and output side switches are associated in pairs so that one command reconfigures both switches, thereby reducing the number of commands that must be sent. However, this system still introduces differences in line length when the redundant amplifier is activated.
The additional line lengths characteristic to the aforementioned systems cause increased signal loss and introduce at least both a small amplitude error and a phase error.
The disadvantages associated with current amplifier redundancy systems have made it apparent that a new system is needed. The new system should substantially minimize line lengths and should also decrease amplitude and phase errors of signals traveling through a matrix amplified system. The present invention is directed to these ends.